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Add missing documentation for argument of amcostestimate()

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5262f7a4fc44 have introduced parallel index scan.  In order to estimate the
number of parallel workers, it adds extra argument to amcostestimate() index
access method API function.  However, this extra argument was missed in the
documentation.  This commit fixes that.

Discussion: https://postgr.es/m/4128fdb4-8b63-2e05-38f6-3125f8c27263%40lab.ntt.co.jp
Author: Tatsuro Yamada, Alexander Korotkov
Backpatch-through: 10
This commit is contained in:
Alexander Korotkov 2018-08-10 14:14:36 +03:00
parent da1a5da1e4
commit 26853a86ae
1 changed files with 19 additions and 3 deletions
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22
doc/src/sgml/indexam.sgml
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@ -383,7 +383,8 @@ amcostestimate (PlannerInfo *root,
Cost *indexStartupCost,
Cost *indexTotalCost,
Selectivity *indexSelectivity,
double *indexCorrelation);
double *indexCorrelation,
double *indexPages);
</programlisting>
Estimate the costs of an index scan. This function is described fully
in <xref linkend="index-cost-estimation">, below.
@ -1151,7 +1152,8 @@ amcostestimate (PlannerInfo *root,
Cost *indexStartupCost,
Cost *indexTotalCost,
Selectivity *indexSelectivity,
double *indexCorrelation);
double *indexCorrelation,
double *indexPages);
</programlisting>
The first three parameters are inputs:
@ -1193,7 +1195,7 @@ amcostestimate (PlannerInfo *root,
</para>
<para>
The last four parameters are pass-by-reference outputs:
The last five parameters are pass-by-reference outputs:
<variablelist>
<varlistentry>
@ -1232,6 +1234,15 @@ amcostestimate (PlannerInfo *root,
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>*indexPages</parameter></term>
<listitem>
<para>
Set to number of index leaf pages
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
@ -1279,6 +1290,11 @@ amcostestimate (PlannerInfo *root,
table.
</para>
<para>
The <parameter>indexPages</parameter> should be set to the number of leaf pages.
This is used to estimate the number of workers for parallel index scan.
</para>
<para>
When <parameter>loop_count</> is greater than one, the returned numbers
should be averages expected for any one scan of the index.